A wide variety of computer systems employ an ability to write data to and read from a remote storage medium, which can provide a number of system advantages. For example, in a distributed client/server storage environment, the ability to write data to a remote storage medium allows an application program to use hardware that is associated with processors other than the one the application program is running on.
One difficulty in accessing data from a storage medium arises from the difference between blocks which comprise a physical expression of data in the storage medium and records which are a logical expression of the data. Within a given block, there may only comprise a part of a record (herein referred to as a "segment"), an entire record or multiple records. The ability to access storage medium data by moving backward through the blocks of a tape is readily provided because blocks are the physical storage unit on the storage medium, such as a direct access storage device (DASD). If, however, an application program on a computing node coupled to the storage medium wishes to skip access records of the file rather than blocks, there is no convenient technique for accomplishing this. Again, there may be several records per block, or in the case of variable blocked spanned (VBS) format records, a logical record may be spread out over several physical blocks.
Thus, an enhanced approach to skipping through the physical blocks of a storage medium based upon logical records contained therein is desired, and in particular, a capability for skipping backwards using logical records is needed.